I see a lot of people who seem to be afraid to touch the electrical parts of their bikes - and to me, that's the easiest thing to fix. A lot of the fear is based on a lack of knowledge. Let me try to help.

Part 1: Voltage and Amperage

This voltage and amperage stuff is simple if you equate it to water: voltage = water pressure, amperage = water volume.

In order to move a large volume of water, you need a big pipe (i.e. a thick wire). On the other hand, you can have any amount of pressure (voltage) you want, regardless of pipe (wire) size. You can put 10,000 psi of water pressure into a pipe the size of a straw. Similarly, you can put 10,000 volts of electricity into a wire the size of a human hair. Of course, if the wall of the pipe isn't strong enough to contain 10,000 psi of pressure, it will rupture, and water will spray out. Similarly, if the thin wire doesn't have strong enough insulation, voltage can "spray" through the insulation and arc (a big spark) to a nearby grounded point.

But for this example, let's say we have a standard 3/4" household water pipe. We have 12 psi of water pressure behind it, and it is capable of moving a volume of 20 ounces of water per second. At the end of the pipe is connected a small water-driven turbine wheel. This turbine wheel, at maximum capacity, can utilize 15 oz of water per second. In the middle of the pipe is a valve, which is turned off. The pressure is still 12 psi, and the volume is zero, because no water is flowing.

Water and turbine - closed valve

Then the valve is opened wide, so there is no restriction. Water flows into the turbine at 15 oz per second, because that is the maximum capacity that it can consume. Because we are not utilizing the full capacity of the water supply, the water pressure remains very close to 12 psi, and there is excess volume capacity.

Water and turbine - open valve

Now let's put a second turbine on the end of the pipe, in addition to the first one. The two turbines combined can utilize 30 oz of water per second. However, the water supply is only capable of supplying 20 oz per second. As a result, each turbine gets only 10 oz per second. Another important thing happens: the water pressure DROPS. The full 12 psi of water pressure is only available when NO water is being consumed. As more and more water is being consumed, the pressure available to push it through the pipe drops slightly. When we get to the point where the devices consuming the water can consume more water than can be supplied, the pressure drops dramatically.

Water and two turbines - open valve

Now let's close the valve halfway. The volume of the water drops to 10 oz per second, because that is all the valve will allow through. The turbines are still demanding 15 oz per second each - but now they are each only getting 5 oz per second - which might not even be enough to spin them. The water pressure in the pipe between the valve and the turbines will be getting close to zero.

Water and two turbines - semi-closed valve

Next, let's look at this exact same scenario, as it applies to electricity:

Instead of a water pipe, we have a 14 gauge wire. Instead of 12 psi of water, we have a battery, supplying 12 volts of electricity. Instead of a capacity of 20 oz per second of water, the battery is capable of supplying 20 amps of electrical current. At the end of the wire, is connected a small electric motor. This motor, when under full load, can draw 15 amps. In the middle of the wire is a switch, which is turned off. There is still 12 volts available, but the amperage is zero, because no current is flowing.

Then the switch is turned on, so there is no restriction. Electricity starts flowing into the electric motor at 15 amps, because that is the maximum current that it can draw. Because we are not utilizing the full capacity of the battery, the voltage remains very close to 12 volts, and there is excess current capacity.

Now let's put a second electric motor on the end of the wire, in addition to the first one. The two motors together can draw 30 amps of current. However, the battery is only capable of supplying 20 amps. As a result, each motor draws only 10 amps. Another important thing happens: the voltage DROPS. Full voltage is only available when NO power is being consumed. As more and more power is being consumed, the voltage available to push it through the pipe drops slightly. When the devices consuming the power can consume more current than can be supplied, the voltage drops dramatically.

Now instead of a switch, let's put a resistor - which is the same as a partly-closed valve. The current flowing in the wire drops to 10 amps, because that is all the resistor will allow through. The electric motors are still requiring 15 amps each - but now they are each only getting 5 amps - which might not even be enough to spin them under load. The voltage between the resistor and the motors will be getting close to zero.

You can see the parallels. In the real world, instead of a resistor, it could be a frayed wire, a dirty connector, a corroded terminal, or any of a number of other things that impede the flow of electricity. One other thing happens: the thing impeding the flow heats up, from friction. This actually happens in the water valve as well, but it's practically undetectable, because the water flow carries the heat away. In the electrical world, the resistor (or connector, or wire) heats up. And as the resistor heats up, it starts resisting the flow of current even more. A good example of this is the infamous "three yellow wires" connecting the stator to the rectifier in our four-cylinder Wings. The connectors get dirty, and start acting as a resistor. As a result, they heat up, and eventually get hot enough to melt the connectors.

Let's look at it as it applies to the starter motor. You have a battery, supplying 12 volts, and capable of supplying 300 amps (for short bursts). You have a wire going through the solenoid (essentially just a switch), and then to the starter motor, which can consume lots of amps (I don't know the exact amount, let's say it's 200).

You hit the starter button, it closes the solenoid, allowing the current to flow to the starter. It, under load (because it's turning the engine), draws 200 amps, and everything is fine.

However, now let's say the solenoid is faulty - it is acting as a resistor. It is restricting the amount of current available to the starter to say, 150 amps. Because the starter is demanding 200, and only 150 is being given to it, the voltage drops considerably. If you attach a voltmeter, you will see close to a full 12 volts BEFORE the solenoid, and something more like 6 or 7 volts AFTER the solenoid. Now you know the solenoid is the problem.

And as to why a free-spinning starter tells you nothing? Electric motors draw almost nothing when run with no load. They draw the MOST current when they are stopped dead. The faster they spin (meaning the less load they have to turn), the less current they draw. So if you hook up your free-spinning starter to your starting system, press the button, and everything sits happily at 12 volts - well, that's because the starter is only drawing 5 amps of current, well within the capacity of whatever the thing is that is acting as a resistor (in our example, the solenoid).

And lastly, why should you not run your starter for more than a few seconds when starting your motorcycle? The windings (coils of wire) inside it, that act as a giant electromagnet, causing it to spin - are basically one giant resistor. And remember what happens to resistors when a lot of current is being pulled through them? They get hot. And in this case, we're talking 200 amps, which is an enormous amount of current, so your starter gets very hot, very fast. Give it some time to cool off before trying again.

If I'm allowed..I'll add a little too....If not..by all means...delete this post...

The common idea is the "red" wire is the "hot" wire....In DC electronics reality,, it is not...
Electricity(moving electrons) is provided from the negative terminal of the battery...The electrons actually flow through the frame to all the individual grounds,into the "load"..(ex.light bulb) and then return to the positive lug of the battery....

The main reason to ensure all the "grounds" are clean and tight....There the source of the "power" needed to operate the load....

One other thought...electrons travel best on the surface of a conductor,not up the middle...So in reality a #12 solid copper wire will carry less "power" than a #12 fine stranded copper wire...
Strange but true...the #12 fine strand wire has much more surface area for the electrons to travel on....
Negative(ground)= excessive electrons
Positive(hot)= lack of electrons
Electrons travel from negative to positive to complete the circuit...

What a nice surprise to actually hear that others are willing to learn about this magic some take for granted and understand...

I read too often of owners spending there gas money on parts to try and fix something when just a basic understanding of electric and the meters would have narrowed the problem...

Maybe a electricity 102 tutorial of basic test equipment and readings.....
With cheap Walmart/Harbor Freight stuff that anybody can get...
How and when to use (or not use) a DVM,Analog volt meter,Test probe..
Why use one rather than another,etc...

The common idea is the "red" wire is the "hot" wire....In DC electronics reality,, it is not...
Electricity(moving electrons) is provided from the negative terminal of the battery...The electrons actually flow through the frame to all the individual grounds,into the "load"..(ex.light bulb) and then return to the positive lug of the battery....

The main reason to ensure all the "grounds" are clean and tight....There the source of the "power" needed to operate the load....

One other thought...electrons travel best on the surface of a conductor,not up the middle...So in reality a #12 solid copper wire will carry less "power" than a #12 fine stranded copper wire...
Strange but true...the #12 fine strand wire has much more surface area for the electrons to travel on....
Negative(ground)= excessive electrons
Positive(hot)= lack of electrons
Electrons travel from negative to positive to complete the circuit...

I just finished a class on physical science for my B.S. degree, and can’t resist adding to this thread what I’ve learned.
The reason current (electrons) flows from a battery’s negative terminal to the positive terminal is because of the atoms in the battery. An atom is made up of three primary parts: a neutrally charged neutron, a positively charged proton, and negatively charged electron. When an atom has more protons (+) than electrons (-), it is said to have a positive charge. So the positive post of the battery has many many positively charged atoms or molecules that have more protons than electrons. The negative post has atoms that have more electrons (-) than protons (+). When you connect the two posts together, through a light, motor, or other load, the electrons in the negative side try to return to a neutral state by moving their excess electrons to the positive post’s atoms that are lacking electrons. In other words, the atoms try to balance the number of protons and electrons of both sides until they are no longer charged positive or negative. Once this happens, the battery is dead, or has no charge, so current (electron) flow stops.

My understanding of current flow was negative to positive with in the battery (ie negative plate to positive plate). Therefore outside the battery current flows from the positive terminal and returns to the negative terminal. Current flows to the load and then to ground which is the frame. Please correct me if I'm wrong.

I stand corrected. After reading up on battery physics, Virgil is right on! If you really want to confuse yourself read up on conventional flow notation vs current flow notation. It will take you back to Ben Franklin days and a half hour of your day you'll never get back. Virgil, You the Man!

So which way does lighting flow? Ground to sky, or sky to ground? Where is the conductor,resistance,battery(source)? How did ole Ben Frank not get electrocuted when flying that kite?(no rubber shoe soles) If wood is a bad conductor then why do they say don't stand under a tree in lighting storm? The ponderings of a bored mind

Blackngold wrote:So which way does lighting flow? Ground to sky, or sky to ground? Where is the conductor,resistance,battery(source)? How did ole Ben Frank not get electrocuted when flying that kite?(no rubber shoe soles) If wood is a bad conductor then why do they say don't stand under a tree in lighting storm? The ponderings of a bored mind

Everything is a conductor. Just some substances are a much better conductor than others. Air is a very poor conductor, but if you get the voltage high enough, it will conduct - and the result is a spark (or a BIG spark, otherwise known as lightning). Wood is a bad conductor, but much better than air, so lightning will prefer it (lightning will search out the shortest path to ground, so if a tree makes that path shorter by 30 feet, it will pick that tree). Wet wood is a much better conductor than dry wood. In fact, wet anything is a fairly decent conductor, because water is a reasonable conductor as well. Salty water is an excellent conductor, which is why salt water causes rust - rust is an electrical process.

Your body is primarily a bag full of salty water, which makes an EXCELLENT conductor. So don't stand out in a field in a lightning storm.

If I'm allowed..I'll add a little too....If not..by all means...delete this post...

The common idea is the "red" wire is the "hot" wire....In DC electronics reality,, it is not...
Electricity(moving electrons) is provided from the negative terminal of the battery...The electrons actually flow through the frame to all the individual grounds,into the "load"..(ex.light bulb) and then return to the positive lug of the battery....

The main reason to ensure all the "grounds" are clean and tight....There the source of the "power" needed to operate the load....

One other thought...electrons travel best on the surface of a conductor,not up the middle...So in reality a #12 solid copper wire will carry less "power" than a #12 fine stranded copper wire...
Strange but true...the #12 fine strand wire has much more surface area for the electrons to travel on....
Negative(ground)= excessive electrons
Positive(hot)= lack of electrons
Electrons travel from negative to positive to complete the circuit...

With all due respect, I have a real problem with the amp capacity vis a vis the wire gauge / stranded vs solid core.
Seems to me, and electrical charts show this, a #12 multi-core (stranded) wire is rated less than a #12 solid core wire in terms of current load capacity.
For example: where a 2.05 mm thick single core wire has a current load rating of 34 amps, the same gauge 4-6 core wire is rated for only 16 amps. This is so, because of the air gaps between the strands. Therefore in order to achieve the same amp capacity as a solid wire, the stranded wire must be of a thicker gauge!

The common idea is the "red" wire is the "hot" wire....In DC electronics reality,, it is not...
Electricity(moving electrons) is provided from the negative terminal of the battery...The electrons actually flow through the frame to all the individual grounds,into the "load"..(ex.light bulb) and then return to the positive lug of the battery....

Not questioning your comment at all because I do not have enough knowledge to do so...

But if negative is where the currents come out of the battery, why do we put switches, resistors, bulbs, LEDs, fuses, etc on the positive side? What you are saying is counterintuitive to me.

I have worked with electricity (Some AC, but mostly DC) for many many years. It does not mean I actually know anything, which is why I am asking.

The common idea is the "red" wire is the "hot" wire....In DC electronics reality,, it is not...
Electricity(moving electrons) is provided from the negative terminal of the battery...The electrons actually flow through the frame to all the individual grounds,into the "load"..(ex.light bulb) and then return to the positive lug of the battery....

Not questioning your comment at all because I do not have enough knowledge to do so...

But if negative is where the currents come out of the battery, why do we put switches, resistors, bulbs, LEDs, fuses, etc on the positive side? What you are saying is counterintuitive to me.

I have worked with electricity (Some AC, but mostly DC) for many many years. It does not mean I actually know anything, which is why I am asking.

Thanx!

Please draw (picture) this circuit: Battery, light bulb and two lengths of wire connecting the bulb to the battery +/-. Now tell us which side of the circuit the bulb is connected to + or - ?

Tom

A well regulated Militia, being necessary to the security of a free State, the right of the people to keep and bear Arms, shall not be infringed.

I think the issue of electron flow is a nice to know aspect of the DC system. Practically, and for us layman who use and work on these systems, consistency is more the issue. Making sure that any additional device installations are connected as per the original design is the accepted norm. Controlling the input or the output to a DC device is dependent on the application and its location.

Using conventional thought, right or wrong - positive to negative, we tend to size the positive wires for the amperage of the device being installed and should do similarly for the negative side - electrics 101.

Using the convention that negative is ground, I have looked at and have found that there are 2 ground locations on my '85 LTD. The main ground is between the battery and engine/frame - generally 6/8 GA wire - mine is 8 GA (new). The second ground location is just forward of the regulator above the coils on the left side of the frame. This second location is a threaded boss welded to the frame. There is a 16/18 GA wire attached to this threaded boss and is the only ground wire for the entire electrical system wiring harness. I mention this because in the various OEM service manuals there are ground connection locations mentioned; however, these locations are where wires are joined in the electrical system wiring harness, not to the bike frame. These wires and the various connections all funnel out of the wiring harness to the ground location on the frame just forward of the regulator through a 16/18 GA sized wire.

Whichever way the electrical current flow is, I submit that this ground wire connection is too small in wire gauge size to handle the electrical system current flow. The positive side of the electrical system has wire gauge sizes that are generally sized for the device amperage requirements.

Having mentioned this, I would think that the grounding requirements for the system, even if the system appears to be working well, could be dramatically improved with a properly sized ground circuit considering that the electrical system as a whole is rated at 30 amps. Doing this might result in a better operating electrical system.

Just thinking out loud with a few thoughts I now need to look at further.

Cheers

"When you write the story of your life, don't let anyone else hold the pen"

Ernest has given a very good description of the What, How, and Why of what is happening.

Which direction the electrons flow is only important in Electrolysis as far as us motorcyclists are concerned. The little bubbles go from negative towards the positive post of the battery.

As Ernest has mentioned, all of those little "ground points" are just merged wires towards a truly "grounded wire" which is the Boss that he mentions.

30+ year old wiring exposed to the elements will corrode, and each of the grounding points needs to be looked at and make sure they are free of corrosion. White Distilled Vinegar and a small brush works wonders.

on bigger stuff, baking soda and a tiny bit of water and the brush helps to remove crud.

On the actual Battery Terminals, I spray them with a product that helps to prevent them from corroding. Very important on my Electric Golf cart.... six of those 6 volts batteries in series on that thing.... I inspect them for proper water level often.

The common idea is the "red" wire is the "hot" wire....In DC electronics reality,, it is not...
Electricity(moving electrons) is provided from the negative terminal of the battery...The electrons actually flow through the frame to all the individual grounds,into the "load"..(ex.light bulb) and then return to the positive lug of the battery....

Not questioning your comment at all because I do not have enough knowledge to do so...

But if negative is where the currents come out of the battery, why do we put switches, resistors, bulbs, LEDs, fuses, etc on the positive side? What you are saying is counterintuitive to me.

I have worked with electricity (Some AC, but mostly DC) for many many years. It does not mean I actually know anything, which is why I am asking.

Thanx!

It doesn't matter which side the switches, lights, etc. go, in theory. You need a complete circuit in order for the current to flow.

On our bikes, the negative is used as a "common bus". Years ago there were cars (British, mostly) that were positive ground instead of negative ground - so all the fuses, switches etc. were connected to the negative terminal, and the frame of the car was connected to the positive. As long as it is all consistent.

In effect, you get the exact same effect - either the current flows and does work, or it doesn't (depending on the state of the switch, fuse, etc). Which direction the electrons are flowing is actually irrelevant, unless you are getting into physics, or electroplating.